• Title/Summary/Keyword: Neutron irradiation

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Influence of Fast Neutron Irradiation on the Electrical and Optical Properties of Li Doped ZnSnO Thin Film Transistor (Li 도핑된 ZnSnO 박막 트랜지스터의 전기 및 광학적 특성에 대한 고속 중성자 조사의 영향)

  • Cho, In-Hwan;Kim, Chan-Joong;Jun, Byung-Hyuk
    • Korean Journal of Materials Research
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    • v.30 no.3
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    • pp.117-122
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    • 2020
  • The effects of fast neutron irradiation on the electrical and optical properties of Li (3 at%) doped ZnSnO (ZTO) thin films fabricated using a sol-gel process are investigated. From the results of Li-ZTO TFT characteristics according to change of neutron irradiation time, the saturation mobility is found to increase and threshold voltage values shift to a negative direction from 1,000 s neutron irradiation time. X-ray photoelectron spectroscopy analysis of the O 1s core level shows that the relative area of oxygen vacancies is almost unchanged with different irradiation times. From the results of band alignment, it is confirmed that, due to the increase of electron carrier concentration, the Fermi level (EF) of the sample irradiated for 1,000 s is located at the position closest to the conduction band minimum. The increase in electron concentration is considered by looking at the shallow band edge state under the conduction band edge formed by fast neutron irradiation of more than 1,000 s.

The effect of neutron irradiation on hydride reorientation and mechanical property degradation of zirconium alloy cladding

  • Jang, Ki-Nam;Kim, Kyu-Tae
    • Nuclear Engineering and Technology
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    • v.49 no.7
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    • pp.1472-1482
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    • 2017
  • Zirconium alloy cladding tube specimens were irradiated at $380^{\circ}C$ up to a fast neutron fluence of $7.5{\times}10^{24}n/m^2$ in a research reactor to investigate the effect of neutron irradiation on hydride reorientation and mechanical property degradation. Cool-down tests from $400^{\circ}C$ to $200^{\circ}C$ under 150 MPa tensile hoop stress were performed. These tests indicate that the irradiated specimens generated a smaller radial hydride fraction than did the unirradiated specimens and that higher hydrogen content generated a smaller radial hydride fraction. The irradiated specimens of 500 ppm-H showed smaller ultimate tensile strength and plastic strain than those characteristics of the 250 ppm-H specimens. This mechanical property degradation caused by neutron irradiation can be explained by tensile hoop stress-induced microcrack formation on the hydrides in the irradiation-damaged matrix and subsequent microcrack propagation along the hydrides and/or through the matrix.

Development of User Subroutine Program Considering Effect of Neutron Irradiation on Mechanical Material Behavior of Austenitic Stainless Steels (중성자 조사에 따른 오스테나이트 스테인리스 강의 기계적 재료거동 변화를 고려한 사용자 정의 보조 프로그램 개발)

  • Kim, Jong Sung;Jhung, Myung Jo;Park, Jeong Soon;Oh, Young Jin
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.9
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    • pp.1127-1132
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    • 2013
  • The failure of reactor internals may have a significant effect on the safe operation and shutdown of a reactor. Various agings related to neutron irradiation occur or can potentially occur in the reactor internals owing to high neutron irradiation levels. Austenitic stainless steel, one of the principal materials constituting the reactor internals, shows different mechanical material behaviors such as tensile/creep properties and fracture toughness with neutron irradiation levels. This variation should be considered when the structural integrity of the reactor internals against agings during the design lifetime or continued operation period is evaluated. In this study, user subroutine programs considering the variation of mechanical material behaviors with neutron irradiation levels were developed. The programs were validated by testing them for various conditions.

Change of chemical properties by neutron irradiation in boric acid solution (중성자 조사에 의한 붕산수의 화학특성 변화)

  • Choi, Ke-Chon;Yeon, Jei-Won;Kim, Won-Ho
    • Analytical Science and Technology
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    • v.18 no.4
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    • pp.292-297
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    • 2005
  • The effect of neutron irradiation on the chemical properties was measured in boric acid solution. The pH of the solution decreased in proportion to the irradiation time and the concentration of boric acid. The concentration of hydrogen peroxide, which is one of the radiolysis products of water, is in proportion to the concentration of boric acid, while in inverse proportion to the irradiation time. The oxygen and hydrogen gases had same chemically equivalent ratio in water radiolysis. The lithiun, which comes from $^{10}B(n,{\alpha})^7Li$, had poor relationship with neutron irradiation time at low concentration, $233{\sim}699{\mu}g/mL$, of boric acid, but the relationship was improved at higher concentration.

Study on Changes of Sperm Count and Testis Tissue in Black Mouse after Neutron Irradiation (중성자 조사후 Black mouse의 고환 조직 및 정자수 변화에 관한 연구)

  • Chun, Ki-Jung;Seo, Won-Sook;Son, Hwa-Young
    • Journal of Radiation Protection and Research
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    • v.31 no.1
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    • pp.31-35
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    • 2006
  • For the purpose of the biological effect in black mouse by neutron irradiation, mice were irradiated with 16 or 32 Gy neutron (flux: 1.036739E+09) by tying flat pose at BNCT facility on HANARO Reactor. And 90 days later of irradiation, physical changes of testis and testis tissue were examined. There were no weight changes but a little bit volume changes and sperm counts in the testes. Atrophy of seminiferous tubules irradiated with 32 Gy neutron is increased in number and severity and those in stage VI showed depletion of spermatogonia and pachytene spermatocytes compared to the non-irradiated control group. Testis damage of black mouse was not recovered after long time by 32 Gy neutron irradiation.

Effects of neutron irradiation on superconducting critical temperatures of in situ processed MgB2 superconductors

  • Kim, C.J.;Park, S.D.;Jun, B.H.;Kim, B.G.;Choo, K.N.;Ri, H.C.
    • Progress in Superconductivity and Cryogenics
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    • v.16 no.1
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    • pp.9-13
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    • 2014
  • Effects of neutron irradiation on the superconducting properties of the undoped $MgB_2$ and the carbon(C)-doped $MgB_2$ bulk superconductors, prepared by an in situ reaction process using Mg and B powder, were investigated. The prepared $MgB_2$ samples were neutron-irradiated at the neutron fluence of $10^{16}-10^{18}n/cm^2$ in a Hanaro nuclear reactor of KAERI involving both fast and thermal neutron. The magnetic moment-temperature (M-T) and magnetization-magnetic field (M-H) curves before/after irradiation were obtained using magnetic property measurement system (MPMS). The superconducting critical temperature ($T_c$) and transition width were estimated from the M-T curves and critical current density ($J_c$) was estimated from the M-H curves using a Bean's critical model. The $T_cs$ of the undoped $MgB_2$ and C-doped $MgB_2$ before irradiation were 36.9-37.0 K and 36.6-36.8 K, respectively. The $T_cs$ decreased to 33.2 K and 31.6 K, respectively after irradiation at neutron fluence of $7.16{\times}10^{17}n/cm^2$, and decreased to 22.6 K and 24.0 K, respectively, at $3.13{\times}10^{18}n/cm^2$. The $J_c$ cross-over was observed at the high magnetic field of 5.2 T for the undoped $MgB_2$ irradiated at $7.16{\times}10^{17}n/cm^2$. The $T_c$ and $J_c$ variation after the neutron irradiation at various neutron fluences were explained in terms of the defect formation in the superconducting matrix by neutron irradiation.

Neutron Irradiation Effects on the Magnetic Properties in Fe87Zr7B6 Amorphous Alloy (비정질 Fe87Zr7B6 합금의 중성자 조사량에 따른 자기적 특성변화)

  • Kim, Kyeong-Sup;Kim, Hyo-Chol;Yu, Seong-Cho
    • Journal of the Korean Magnetics Society
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    • v.15 no.1
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    • pp.12-16
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    • 2005
  • The $Fe_{87}Zr_{7}B_{6}$ amorphous alloy after neutron irradiation are studied hysteresis loop and complex permeability measurements. The total integration fluence of fast neutrons is varied from $1.92{\times}10^{14}$ to $4.85{\times}10^{16}n_{f1}cm^{-2}$. After neutron irradiation, the imaginary part of complex permeability in low frequency region decreased due to the decrease of wall motion, but the permeability in high frequency region increased due to the enhancement of rotational magnetization. The measurement of hysteresis loop showed the increase of magnetic softness, related to rotational magnetization, but saturation magnetization was decreased in neutron irradiation sample.

A Study on Point Defect Induced with Neutron Irradiation (중성자 조사에 의해 생성된 점결함 연구)

  • 김진현;이운섭;류근걸;김봉구;이병철;박상준
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.3 no.3
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    • pp.165-169
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    • 2002
  • Silicon wafer is very important accuracy make use semiconductor device substrate. In this research, for the uniformity dopant density distribution obtained to Neutron Transmutation Doping on make use Si in P Doping study work. In this research. we irradiated neutron on FZ silicon wafers which had high resistivity (1000~2000 ${\Omega}$cm), HANARO reactor was utilized resistivity changes due to observed, the generation of neutron irradiation on point defect analyzed, point defect on resistivity changes inquire into the effect. Before neutron irradiation theoretical due to calculated 5 ${\Omega}$-cm, 20.1 ${\Omega}$-cm for HTS hole and 5 ${\Omega}$-cm, 26.5 ${\Omega}$-cm, 32.5 ${\Omega}$-cm for IP3 hole. After neutron irradiation through SRP measurement the designed resistivities were approached, which were 2.1 H-cm for HTS-1, 7.21 ${\Omega}$-cm for HTS-2, 1.79 ${\Omega}$-cm for IP-1, 6.83 ${\Omega}$-cm for IP-2, 9.23 ${\Omega}$-cm for IP-3, respectively. Also after neutron irradiation resistivity changes due to thermal neutron dependent irradiation hole types free.

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A Microstructural Design and Modeling of Neutron-Irradiated Materials (중성자 조사재의 미세구조 설계와 모델링)

  • Chang, Kunok
    • Applied Chemistry for Engineering
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    • v.31 no.4
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    • pp.347-351
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    • 2020
  • A material changes its physical and chemical properties through the interaction with radiation and also the neutrons, which is electronically neutral so that the penetration depth is relatively deeper than that of other radioactive way including alpha or beta ray. Therefore, the radiation damage by neutron irradiation has been intensively investigated for a long time with respect to the safety of nuclear power plants. The damage induced by neutron irradiation begins with the creation of point defects in atomic scale in the unit of picoseconds, and their progress pattern can be characterized by microstructural defects, such as dislocation loops and voids. Their morphological characteristics affect the properties of neutron-irradiated materials, therefore, it is very important to predict the microstructure at a given neutron irradiation condition. This paper briefly reviews the evolution of radiation damage induced by neutron irradiation and introduces a phase-field model that can be widely used in predicting the microstructure evolution of irradiated materials.